The field of the disclosure relates generally to electrostatic painting, and more specifically, to an electrostatic painting apparatus including a plurality of rotary atomizers.
At least some known manufacturing processes use rotary atomizers mounted to robotic arms to apply a coating material (e.g., paint) to a substrate (e.g., a vehicle body). Using robots increases assembly line speeds and increases the rate at which coating material is supplied to the substrate. The robots are programmed to follow contours of the substrate while maintaining a constant distance between the rotary atomizers and the substrate.
Industry demand has pushed for smaller painting arrangements, resulting in paint applications systems that include fewer robots and fewer rotary atomizers. In order to maintain painted substrate output at a desired level, the rotary atomizers and robots are operated at higher speeds with higher coating material application rates. For example at least some known atomizers operate at rotation speeds of 40,000-70,000 revolutions per minute (rpm). Rotation speeds this fast impart high centripetal force on the emitted paint particles, and increase the pressures/volumes of shaping air needed to control the flow of the particles. Further, robots may have motion speeds up to 1200 millimeters per second (mm/sec) to maintain pain application system output at a desired level. However, high robot motion speeds may add a side force to the paint pattern, causing the pattern to trail behind the atomizer. This may be overcome with higher pressures/volumes of shaping air, which consequently may cause particles to bounce off of the substrate instead of attaching to the substrate.
Typically, a separate high voltage power supply is used to provide power to each atomizer involved in the painting process (i.e., one high voltage power supply per atomizer). To prevent high voltage arcing, for every 10 kV potential difference, components should be separated by approximately one inch. For separate electrostatic rotary atomizers having separate high voltage cascades, at least a slight potential difference between the atomizers occurs. Accordingly, such rotary atomizers should be sufficiently separated to prevent high voltage arcing between them. For example, if 70 kV is applied to two atomizers by two separate high voltage power supplies, the atomizers would need to be spaced a minimum of seven inches apart from one another to avoid arcing. Accordingly, for atomizers having separate high voltage power supplies, in order to prevent arcing, relatively compact arrangements of the atomizers may not be possible.
Accordingly, at least some known electrostatic painting systems include robots running at high motion speeds, with high paint material delivery rates, high atomizer rotation speeds, and high pressure/volume shaping air. Operating at these high parameters is relatively expensive and complicated, and may ultimately negate the benefits of electrostatic painting